textproduct: Rapid City

KEY MESSAGES

- Isolated to scattered severe thunderstorms possible across much of the area this afternoon/evening. Main hazards will be large hail (1+" in diameter) and damaging wind gusts (60+ mph)

- Isolated to scattered severe thunderstorms possible again on Saturday with the highest risk across northwestern SD. Main hazards will be very large hail (1 3/4+" in diameter) and significant wind gusts (74+ mph). An isolated tornado also can't be ruled out.

- Isolated severe storms possible on Sunday across much of northeastern WY into western SD.

DISCUSSION

(This Evening Through Friday) Issued at 135 PM MDT Fri Jun 26 2026

Visible satellite shows cumulus struggling to develop over the Black Hills with midlevel clouds moving in from northeastern WY. Current mesoscale analysis shows nose of 500-1000 J/kg ML CAPE pushing into southwestern SD with 150-200 J/kg CIN. The 18z sounding from KUNR shows ~1000 J/kg SB CAPE with a strong cap. While short range model guidance shows increasing ML CAPE over western SD into northeastern WY through this afternoon with 1500- 2000 J/kg ML CAPE over much of western SD into portions of the Black Hills by later this afternoon into this evening, 500 mb height rises and warm 700 mb temps may limit convective development across much of our CWA. Most recent CAMs show convection developing over the higher terrain in WY and moving into northeastern WY by later this afternoon. Inverted-V profiles and low level curvature in forecast hodographs indicate a damaging wind and large hail threat. Storms will push east into western SD by this evening, moving out of the CWA by midnight.

Severe potential continues on Saturday as a shortwave and attendant lee sfc trof/low moves through the region. As the sfc trof deepens over western SD, axis of 2500-3000 J/kg ML CAPE will develop across much of the western SD plains and northwestern SD. The greater shear of 35-45KT will be displaced further west of the greatest instability, though there is some overlap over northwestern SD. Current CAMs show discrete storms firing over southeastern MT and moving into northwestern SD by Saturday evening. These storms will be capable of very large hail (greater than 1 3/4") and significant wind gusts (74+ mph). Tornado threat is low but not zero and an isolated tornado is certainly possible with any discrete supercells that form.

Unsettled southwest flow continues over the CWA through Sunday as the western US trof deepens. This will result in chances for storms (some may be strong to severe) later Sunday into Monday. Additionally, temperatures will continue to warm through this weekend with highs in the 80s to 90s by Saturday and Sunday. After a slight cool down on Monday, ensemble guidance is signaling much warmer weather with daily chances for isolated storms later in the week as a ridge builds to our east.

AVIATION

(For the 18Z TAFS Through 18Z Saturday) Issued At 1114 AM MDT Fri Jun 26 2026

Areas of MVFR CIGS from K2WX-KD07-KICR will dissipate this afternoon. Scattered TSRA will develop over northeastern WY/northern Black Hills by 26z/21z (including the KGCC terminal) and then track east/northeast with local IFR conditions, including strong erratic winds/hail. Chance of TSRA for KRAP is lower, but did include a prob30 to account. IFR CIGS will develop along/east of a line from KD07-KICR later tonight. Outside of these areas, expect VFR conditions.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.